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HEMA 1 LEC > Unit 3.4 HEMATOCRIT (HCT) MEASUREMENT; RBC INDICES > Flashcards

Unit 3.4 HEMATOCRIT (HCT) MEASUREMENT; RBC INDICES Flashcards

1
Q

refers to the proportion of whole blood that consists of red blood cells, expressed as a percentage of the total blood volume.

A

Hematocrit (packed cell volume/PCV)

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2
Q

provides the clinicians with an estimate of the bods red cell volume and thus, the bloods ogen-carrying capacity.

A

Hematocrit

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3
Q

is useful in screening for, diagnosing, or monitoring a number of conditions and diseases that affect the proportion of blood (e.g. anemias).

A

Hematocrit determination

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4
Q

Other uses of hematocrit:

A

Used in the calculation of Absolute indices/constants
In rough Quality Control calculations
The buffy coat portion can be used in the preparation of buffy coat smears.

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5
Q

Hematocrit Reference ranges:
Male:
Female:

A

0.42 - 0 .50 / 41.5 - 50.4%
0.36 - 0.45 / 35.9 - 44.6%

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6
Q

Indirect Hct Calculated as:

A
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7
Q

Direct (Manual/Spun Hct) Computed as:

A
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8
Q

Microhematocrit tube
Length: _________

A
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9
Q

Microhematocrit tube
Bore: _________

A
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10
Q

Microhematocrit tube
Blood column:

A

at least 5 cm

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11
Q

Microhematocrit tube
Plug/Seal: ________

A
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12
Q

Microhematocrit tube
Centrifugation (RCF): __________

A
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13
Q

Wintrobe Tube
Length: ___________

A
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14
Q

Wintrobe Tube
Graduations:
Left: __________________
Right: __________________

A
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15
Q

Wintrobe Tube
Diameter: _____________

A
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16
Q

Wintrobe Tube
Centrifugation (RCF): __________

A
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17
Q

Technical Errors

A

Excess anticoagulant - leads to RBC shrinkage
Prolonged-standing of blood sample prior to test
Insufficient mixing of blood
Improper sealing of tube leads to escape of red cells
Inadequate centrifugation/allowing the tubes to stand too long after centrifugation
Reading errors (e.g. parallax error)

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18
Q

Physiologic Errors

A

Trapped plasma increases the packed cell volume/height
Values taken immediately after acute blood loss
Dehydration leads to plasma loss
Stasis which leads to hemoconcentration

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19
Q

To check the accuracy of the RBC, Hb, and Hct values generated by an automated analyzers or by manual methods.

A

RULE OF THREE:

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20
Q

The rules of three applies only to RBCs that are normal in

A

size and hemoglobin content

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21
Q

RULE OF THREE: BASIC FORMULA

A
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22
Q

If values are WITHIN and the RBCs are normocytic, normochromic =

A

report results

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23
Q

If values are NOT within & the RBCs are abnormal in shape & hemoglobin content =

A

report results

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24
Q

If values are NOT within but the RBCs are normocytic, normochromic =

A

Do NOT report

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25
Q

Used to define the size and hemoglobin content of the red blood cell.

A

RBC INDICES

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26
Q

Used in classifying types of anemia

A

RBC INDICES

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27
Q

refers to the average volume of the individual red cells in a given blood sample

A

MCV (Mean Corpuscular/Cell Volume)

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28
Q

Used as an estimation of the average size of the RBC

A

MCV (Mean Corpuscular/Cell Volume)

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29
Q

Not dependable when RBCs vary markedly in size

A

MCV (Mean Corpuscular/Cell Volume)

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30
Q

MCV =

A
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31
Q

MCV = Reference Value:
= Cells are microcytic
= Cells are macrocytic

A

80 - 100 fL
< 80 fL
> 100 fL

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32
Q

MCHC =

A
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33
Q

MCHC = Reference Value:
= Cells are hypochromic
= Cells are spherocytic

A

320 - 360 g/L or 32 - 36 %
< 32%
36%

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34
Q

MCH =

A
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35
Q

MCH = Reference Value:

A

27 - 33 pg

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36
Q

refers to average Hb concentration of red cells in a given volume of blood

A

MCHC (Mean Cell Hemoglobin Concentration)

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37
Q

The average weight of Hb per RBC

A

MCH (Mean Cell Hemoglobin)

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38
Q

Always correlate with the MCV & MCHC

A

MCH (Mean Cell Hemoglobin)

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39
Q

Directly proportional to the size of the RBC & the concentration of Hgb. in the cell.

A

MCH (Mean Cell Hemoglobin)

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40
Q

represents the ratio of the standard deviation to the MCV (width of the histogram)

A

RDW (Red Cell Distribution Width)

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41
Q

Index of relative anisocytosis; May also indicate poikilocytosis

A

RDW (Red Cell Distribution Width)

42
Q

RDW (Red Cell Distribution Width)
Reference Value:
indicates variation in sizes

A

11.6 - 14.6 %
> 14.6%

43
Q

Average amount of Hb in each RBC compared w/ the average amount in a normal RBC.

A

Color Index (C.I.)

44
Q

C.I. =

A
45
Q

C.I. = Reference Value:

A

0.9 1.1

46
Q

%Hb =

A
47
Q

% RBC =

A
48
Q

Average size of a red cell as compared with the average size of a normal red blood cell

A

Volume Index (V.I.)

49
Q

V.I. =

A
50
Q

V.I. = Reference value:

A

0.9 1.1

51
Q

% Hct =

A
52
Q

Denotes the average amount of Hb per unit volume of RBC in relation to normal.

A

Saturation Index (S.I.)

53
Q

S.I. =

A
54
Q

S.I. = Reference value:

A

0.80 - 1.20

55
Q

The average diameter of red blood cell in microns.

A

Mean Corpuscular Diameter (MCD)

56
Q

Price Jones Method (Direct micrometry)

A

Mean Corpuscular Diameter (MCD)

57
Q

Mean Corpuscular Diameter (MCD)
Reference value =

A

6-9 microns

58
Q

Average volume of the biconcave disk

A

Mean Corpuscular Average Thickness (MCAT)

59
Q

MCAT =

A
60
Q

MCAT = Reference value:

A

1.7-3.5 microns

61
Q

• Micro Method
• Macro Method

A

Direct (Manual/Spun Hct)

62
Q

Wintrobe method

A

Double oxalate

63
Q

Haden’s method

A

1.1% Na Oxalate

64
Q

Van Allen

A

1.6% Na Oxalate

65
Q

Sanford Magath Method

A

1.3% Na Oxalate

66
Q

Bray’s Method

A

Heparin

67
Q

Adams Micromethod

A

Heparin

68
Q

Wintrobe Tube Sample

A

Undiluted anticoagulated blood

69
Q

Westergren Method Sample

Original –
Modified –

A

whole anticoagulated blood w/ 3.8% Na Citrate (4:1)

2.0 mL EDTA blood combined w/ either 0.5 mL NSS or 0.5 mL 3.8% Na Citrate

70
Q

Microhematocrit tube Length

A

75 mm

71
Q

Wintrobe Tube Length

A

115 mm

72
Q

Westergren Tube Length

A

300 mm ± 0.5 mm

73
Q

Wintrobe Tube Internal bore:

A

3 mm

74
Q

Westergren Tube bore:

A

2.65 ± 0.15

75
Q

Westergren Tube Length of blood column:

A

200 mm

76
Q

Microhematocrit tube Diameter:

A

1mm/1.2mm

77
Q

Wintrobe Tube Diameter:

A

3mm

78
Q

Westergren External diameter:

A

5.5 mm ± 0.5 mm

79
Q

Microhematocrit tube RCF:

A

10,000 - 15,000 g for 5 mins

80
Q

Wintrobe Tube RCF:

A

3,000 rpm for 30 mins

81
Q

CLSI Specification of westergren tube:

A

thick-walled glass or hard plastic

82
Q

Disposable Westergren ESR System

A
83
Q

– has a safety plug (non-absorbent material) that provides automatic zeroing

A

Dispette

84
Q

Vol. of capillary tube:

A

0.05 mL (2/3 is filled w/ blood)

85
Q

Wintrobe Tube
2 Graduations:
(right);
(left)

A

Hct
ESR/sedimentation rate scale

86
Q

Distance of tip to band

A

4-6mm

87
Q

Technical Errors

A

• Excess anticoagulant - leads to RBC shrinkage
• Prolonged-standing of blood sample prior to test
• Insufficient mixing of blood
• Improper sealing of tube leads to escape of red cells
• Inadequate centrifugation/allowing the tubes to stand too long after centrifugation (<5 mins = false inc)
• Reading errors (e.g. parallax error – human error)

88
Q
  • leads to RBC shrinkage
A

Excess anticoagulant

89
Q

(EDTA: inv)

A

6-8

90
Q

leads to escape of red cells

A

Improper sealing of tube

91
Q

Physiologic/Physical Errors

A

• Trapped plasma increases the packed cell volume/height – poikilocytes & anisocytes
• Values taken immediately after acute blood loss
• Dehydration leads to plasma loss
• Stasis which leads to hemoconcentration

92
Q

REFERENCE RANGE Hematocrit

A

Male
0.42 - 0 .50

Female
0.36 - 0.45

Children
0.45 – 0.60

93
Q

REFERENCE RANGE Wintrobe

A

Male
0-9 mm/hr

Female
0-20 mm/hr

Children
0-13 mm/hr

94
Q

REFERENCE RANGE Westergren

A

Male
<50 y/o 0 -15 mm/hr
>50 y/o 0 -20 mm/hr

Female
<50 y/o 0 -20 mm/hr
>50 y/o 0 -30 mm/hr

Children 0 - 10 mm/hr

95
Q

↑Hematocrit

A

• Polycythemia vera
• Hemoconcentration
• Dehydration

96
Q

↓ Hematocrit

A

• Anemia
• Hydremia of pregnancy
• Hydration

97
Q

↑MCV

A

• megaloblastic anemia (immature blood cell)
• hemolytic anemia with reticulocytes
• liver disease
• normal in newborns

98
Q

↓MCV

A

• iron deficiency anemia (Pb binds w/ carrier prot of iron)
• thalassemia
• sideroblastic anemia (inc red cell incl)
• lead poisoning

99
Q

↑MCH

A

• macrocytic anemia

100
Q

↓MCH

A

• microcytic anemia

HEMA 1 LEC (15 decks)

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